While divers plunged into a tributary of the Spring River and a helicopter hovered overhead, volunteer searchers went out on horseback, foot and four-wheelers. But by Monday night, there still wasn't any sign of Caleb.

Authorities said Caleb could have wandered off or fallen into the swollen tributary near a bridge where he and several other kids were helping an aunt clear debris left by a recent batch of storms that battered the region.

The kids weren't there as Scouts but to help clear the way for Scouts who spend summers there.

Five of the children, who are related, headed up to the main campsite where they were staying as the aunt watched the grounds while a caretaker was away, Fulton County Sheriff Buck Foley said.

The kids were about 300 yards away when Caleb decided he wanted to join them. His aunt, Rhonda Wright, told him to follow the dirt road and head back to the cabin, Foley said. Then, she went back to clearing debris.

Investigators don't suspect foul play.

Caleb could have fallen in the nearby Spring River tributary, which was saturated with rain from storms that swept the region.

"The way the water's running, you wouldn't hear a splash," Foley said.

Or he could have veered off into the woods or a nearby field on the 1/2-mile trek back to the cabin.

"I think he just wandered off," Foley said.

Even as their third day of searching drew to a close, authorities said they are proceeding under the assumption Caleb is alive.

"It's still a search and rescue," Foley said late Monday.

Yet authorities called in cadaver dogs and set a net downstream that could catch a body if the boy did fall into the river. It's also possible that a body could have passed that point before the net was put up, said Major Todd Smith, the assistant chief of enforcement for the Arkansas Game and Fish Commission.

"It's like looking for a needle in the haystack," Smith said. "There's no way to search the whole river."

But the searchers were trying their hardest and the weather seemed to be cooperating.

The tributary had receded by Monday so divers could get in the water to clear debris from beneath the bridge and look at images from an underwater camera. Plus, the dry weather and moderate temperatures since Saturday sustained the hope of at least some of the searchers, who could be heard in the woods calling out "Caleb!"

Caleb's mother and stepfather, who live 150 miles west of Hardy in Springdale, were at the camp Monday. A couple at a cabin with a stroller and overturned tricycle out front said they were Caleb's parents but that they didn't want to talk.

"We don't want to do any kind of interviews," the man said.

Down by the river, authorities scaled back the number of searchers looking for Caleb overnight, but didn't call off the search.

"We don't want to be looking for people after dark," sheriff's deputy Boyd Dailey said.

No one seemed ready to give up. As dusk fell, people dropped off cases of bottled water and bags of cookies. Police cars and mud-covered pickup trucks lined the dirt road leading down to the river.

Dailey held out hope that maybe Caleb was heeding the advice adults teach children: Don't talk to strangers.

"If he's out there, he's scared, and if he's hiding, maybe he'll pop up and somebody will see him," he said.

He hopped on a four-wheeler and drove up the hill. On the way, an officer flagged him down and asked if there was any news.